 .pagetotop {
    position: fixed;
    right: 50px;
    bottom: 50px;
    z-index: 999;
    display: none;
    color:#fff;
    background-color: rgba(0,0,0,0.6);
}

@media (max-width: 640px) {
  .pagetotop{
        right:10px;bottom:20px;color:#fff;
        background-color:rgba(255,255,255,0.2);
    }
    .pagetotop p{
        display:none;
    }
}